The Ascertainment, Tracing and Tracking (AT&T) Scientific Core requests 5 years of support to provide support to the Missouri Alcoholism Research Center projects in the (i) identification from Missouri state records and (ii) location ('tracing') and follow-up ('retracing') of subjects and family members for epidemiologic, genetic and high-risk studies on alcohol and substance use disorders in adolescence and youth; (iii) monitoring ('tracking') the progress of subjects and their families through research (including follow-up) protocols, and controlling timing of access to subjects involved in more than one protocol; (iv) monitoring staff productivity and research project success in meeting data-collection targets; (v) monitoring of representativeness if samples that are ascertained, and generation of sampling weights to adjust for any systemic sampling biases. In addition, in years 4-5, the AT&T core will take over maintenance of the central computerized state data-bases which are update on a annual basis, and used for subject identification and tracking, services which are now provided through the department's Mental Health Clinical Research Center.